U.S. patent application number 11/715275 was filed with the patent office on 2007-09-20 for semiconductor component arrangement comprising a trench transistor.
This patent application is currently assigned to Infineon Technologies AG. Invention is credited to Franz Hirler, Norbert Krischke, Markus Zundel.
Application Number | 20070215920 11/715275 |
Document ID | / |
Family ID | 38516888 |
Filed Date | 2007-09-20 |
United States Patent
Application |
20070215920 |
Kind Code |
A1 |
Zundel; Markus ; et
al. |
September 20, 2007 |
Semiconductor component arrangement comprising a trench
transistor
Abstract
Disclosed is a semiconductor component arrangement and a method
for producing a semiconductor component arrangement. The method
comprises producing a trench transistor structure with at least one
trench disposed in the semiconductor body and with at least a gate
electrode disposed in the at least one trench. An electrode
structure is disposed in at least one further trench and comprises
an at least one electrode. The at least one trench of the
transistor structure and the at least one further trench are
produced by common process steps. Furthermore, the at least one
electrode of the electrode structure and the gate electrode are
produced by common process steps.
Inventors: |
Zundel; Markus; (Egmating,
DE) ; Hirler; Franz; (Isen, DE) ; Krischke;
Norbert; (Munich, DE) |
Correspondence
Address: |
Maginot, Moore & Beck;Chase Tower
Suite 3250
111 Monument Circle
Indianapolis
IN
46204
US
|
Assignee: |
Infineon Technologies AG
Munich
DE
|
Family ID: |
38516888 |
Appl. No.: |
11/715275 |
Filed: |
March 7, 2007 |
Current U.S.
Class: |
257/288 ;
257/E29.027; 257/E29.121; 257/E29.258; 257/E29.346 |
Current CPC
Class: |
H01L 29/41766 20130101;
H01L 27/0733 20130101; H01L 28/40 20130101; H01L 29/7803 20130101;
H01L 29/407 20130101; H01L 21/743 20130101; H01L 29/66734 20130101;
H01L 29/7816 20130101; H01L 29/0696 20130101; H01L 29/7804
20130101; H01L 29/7809 20130101; H01L 29/945 20130101; H01L 29/7813
20130101 |
Class at
Publication: |
257/288 |
International
Class: |
H01L 29/76 20060101
H01L029/76 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 7, 2006 |
DE |
102006010510.9-33 |
Claims
1. A method for producing a semiconductor component arrangement,
the method comprising: producing a trench transistor structure
including at least one trench disposed in the semiconductor body
and at least one gate electrode disposed in the at least one
trench; producing an electrode structure disposed in at least one
further trench, the electrode structure comprising at least one
electrode; wherein the at least one trench of the transistor
structure and the at least one further trench are produced by
common process steps; and wherein the gate electrode and the at
least one electrode of the electrode structure are produced by
common process steps.
2. The method of claim 1, wherein the trench transistor structure
further comprises at least one field electrode in the at least one
trench, and wherein the electrode structure comprises at least two
electrodes, wherein the at least two electrodes and the at least
one gate electrode and the at least one field electrode are
produced by common process steps.
3. The method of claim 1, wherein the at least one trench of the
trench transistor structure and the at least one further trench are
produced having different trench widths.
4. The method of claim 1, wherein prior to producing the at least
one gate electrode of the trench transistor structure and prior to
producing the at least one electrode of the electrode structure,
dielectric layers are produced on surfaces of the at least one
trench of the trench transistor structure and the at least one
further trench.
5. The method of claim 1, wherein the trench transistor structure
comprises a body zone and a source zone which are adjacent to the
at least one trench of the trench transistor structure, wherein the
body zone and the source zone are produced after producing the at
least one gate electrode.
6. The method of claim 1, wherein the electrode structure is part
of a trench wiring structure.
7. The method of claim 1, wherein the electrode structure is part
of a capacitor structure.
8. The method of claim 1, wherein a gate dielectric is produced on
surfaces of the at least one trench of the trench transistor
structure, and wherein a capacitor dielectric is produced on
surfaces of the at least one further trench.
9. The method of claim 8, wherein producing the capacitor
dielectric comprises the steps of thermally oxidizing surfaces of
the at least one further trench, and protecting the trench
transistor structure against an oxidation by a protection layer
during said thermal oxidation step.
10. The method of claim 9, wherein the gate dielectric is produced
after the removal of the protection layer.
11. A semiconductor component arrangement comprising: a
semiconductor body having a first side and a second side; a trench
transistor structure integrated in the semiconductor body, the
trench transistor structure comprising at least one trench and at
least one gate electrode positioned in said at least one trench; at
least one electrode structure disposed in at least one further
trench, the at least one electrode structure comprising at least
one electrode, wherein at least one section of the at least one
electrode has the same geometrical basic structure as the at least
one gate electrode.
12. The semiconductor component arrangement of claim 11, further
comprising at least two terminal contacts arranged in the
semiconductor body or on the semiconductor body, the at least two
terminal contacts electrically conductively connected to one
another by at least one electrically conductive connection line,
wherein the at least one electrically conductive connection line is
arranged as at least one trench connection line formed by the
electrode structure.
13. The semiconductor component arrangement of claim 12, further
comprising an insulation layer, wherein the insulation layer
comprises a layer stack having at least two layers composed of an
insulation material.
14. The semiconductor component arrangement of claim 12, in wherein
the at least one trench connection line comprises a doped
polycrystalline semiconductor material, a semiconductor-metal
compound or a metal.
15. The semiconductor component arrangement of claim 12, wherein
the at least one trench connection line comprises at least two
trench connection lines arranged in a trench.
16. The semiconductor component arrangement of claim 15, wherein
the at least two trench connection lines are arranged in a manner
spaced apart from one another in a vertical direction of the
semiconductor body.
17. The semiconductor component arrangement of claim 15, wherein
the at least two trench connection lines are arranged in a manner
spaced apart from one another in a horizontal direction of the
semiconductor body.
18. The semiconductor component arrangement of claim 15, wherein
the trench comprises two mutually crossing trenches, wherein a
first of the at least two trench connection lines is arranged in a
first of the two mutually crossing trenches and a second of the at
least two trench connection lines is arranged in a second of the
two mutually crossing trenches.
19. The semiconductor component arrangement of claim 18, wherein
the at least two trench connection lines are arranged in the two
mutually crossing trenches at least in a crossover region of the
trenches at different positions in the vertical direction of the
semiconductor body.
20. The semiconductor component arrangement of claim 18, wherein
the first of the at least two trench connection lines is
electrically conductively connected to the second of the at least
two trench connection lines in a crossover region of the two
mutually crossing trenches.
21. The semiconductor component arrangement of claim 11, wherein at
least one transistor structure having a source zone, a drain zone
and a gate electrode is provided in the semiconductor body, and
wherein at least one of the source zone, the drain zone or the gate
electrode is contact-connected by at least one trench connection
line.
22. The semiconductor component arrangement of claim 11, wherein a
cell array of a power transistor and a temperature sensor are
integrated in the semiconductor body, wherein the temperature
sensor is contact-connected by at least one trench connection
line.
23. The semiconductor component arrangement of claim 22, wherein
the temperature sensor has a first terminal and a second terminal,
the first terminal being contact-connected by a first trench
connection line and the second terminal being contact-connected by
a second trench connection line, the first trench connection line
and the second trench connection line arranged one above another in
a common trench.
24. The semiconductor component arrangement of claim 11, further
comprising a wiring layer above one side of the semiconductor body,
wherein at least two interconnects each having at least one
terminal contact are disposed in the wiring layer, and wherein a
trench connection line respectively contacts one of the terminal
contacts of the interconnects.
25. The semiconductor component arrangement of claim 11, wherein a
diode having an anode zone and a cathode zone is integrated in the
semiconductor body, and wherein at least one of said anode zone and
cathode zone is contact-connected by a trench line connection.
26. The semiconductor component arrangement of claim 11, wherein a
resistance element having a first terminal and a second terminal is
arranged in or on the semiconductor body, at least one of said
first terminal and second terminal being contact-connected by a
trench line connection.
27. The semiconductor component arrangement of claim 11, wherein a
zener diode chain having at least two zener diodes and also a first
terminal and a second terminal and at least one intermediate tap is
arranged in or on the semiconductor body, at least one of said
first terminal and second terminal being contact-connected by a
trench line connection.
28. The semiconductor component arrangement of claim 11, wherein
the at least one electrode structure comprises a capacitor
structure having at least one capacitor electrode arranged in a
trench of the semiconductor body.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from German patent
application no. 10 2006 010 510.9-33, filed Mar. 7, 2006, the
contents of which are incorporated herein by reference.
FIELD
[0002] The present invention relates to a method of producing a
semiconductor component arrangement comprising a trench transistor
and to a semiconductor component arrangement comprising a trench
transistor.
BACKGROUND
[0003] In order to connect a plurality of components in a
semiconductor body or semiconductor chip to one another to form an
integrated circuit or in order to connect the components integrated
in a semiconductor body to terminal contacts for an external
interconnection, connection lines also have to be produced during
the production process for producing of the components.
[0004] In known "smart power IC technologies", that is to say
technologies which enable a realization of power components, in
particular power transistors, and logic components in one
semiconductor chip, often only two wiring levels above one side of
the semiconductor body are available for the realization of such
connection lines or wirings, one of which levels comprises metal
lines, for example, and the other level comprises lines composed of
polysilicon.
[0005] If there are a multiplicity of components in the
semiconductor body, in particular a multiplicity of logic
components, which are to be interconnected with one another, space
problems may occur. In the case of such a circuit, it is necessary
to interconnect individual logic gates, in particular, and also
individual circuit blocks, which may in each case comprise a
plurality of components. What is more, it may be necessary to
produce bridgings by means of which two lines of the metallization
level that are arranged in a manner spaced apart from one another
are conductively connected to one another.
[0006] Depending on the function of the integrated circuit it may
become necessary to realize capacitor structures or further
electrode structures in the same semiconductor body as the trench
transistor.
SUMMARY
[0007] According to one embodiment of the invention, a method for
producing a semiconductor component arrangement comprises producing
a trench transistor structure with at least one trench disposed in
the semiconductor body and with at least a gate electrode disposed
in the at least one trench. In addition, an electrode structure is
disposed in at least one further trench and comprises an at least
one electrode. In this method, the at least one trench of the
transistor structure and the at least one further trench are
produced by common process steps, and the at least one electrode of
the electrode structure and the gate electrode are produced by
common process steps.
[0008] According to another embodiment of the invention, a
semiconductor component arrangement comprises a semiconductor body
having a first side and a second side. A trench transistor
structure is integrated in the semiconductor body and comprises at
least one trench and in said trench at least one gate electrode. At
least one electrode structure is disposed in at least one further
trench and comprises at least one electrode which in at least one
section has the same geometrical structure as the gate
electrode.
[0009] In various embodiments, the electrode structure may be part
of a wiring structure/connection line structure or may be part of a
capacitor structure.
[0010] Within such a trench it is possible to provide a plurality
of separate trench connection lines which are arranged one above
another in the trench in a vertical direction of the semiconductor
body. It is also possible to provide only one trench connection
line in the trench, which trench connection line may then have a
cross section of a size in line with the need for realizing a
low-resistance line connection.
[0011] The trench connection line comprises an arbitrary
electrically conductive material, for example a doped
polycrystalline semiconductor material, such as polysilicon, a
metal-semiconductor compound, such as, for example, a silicide, or
a metal, such as, for example, titanium, tungsten or platinum.
[0012] The above-mentioned features and advantages, as well as
others, will become more readily apparent to those of ordinary
skill in the art by reference to the following detailed description
and accompanying drawings. The teachings disclosed herein extend to
those embodiments which fall within the scope of the appended
claims, regardless of whether they include one or more of the
above-mentioned features or accomplish one or more of the
above-mentioned advantages.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Embodiments of the present invention are explained in more
detail below with reference to figures.
[0014] FIG. 1 shows a wiring concept for an integrated circuit
arrangement according to the prior art.
[0015] FIG. 2 shows a first exemplary embodiment of a semiconductor
component arrangement comprising a trench line connection.
[0016] FIG. 3 shows a semiconductor body with a trench connection
line which connects two interconnects arranged above a surface of
the semiconductor body to one another.
[0017] FIG. 4 shows a cross section through a semiconductor body
with two mutually crossing trench connection lines.
[0018] FIG. 5 shows a cross section through a semiconductor body in
which a lateral MOS transistor is realized, the source and drain
terminals of which are contact-connected by trench connection
lines.
[0019] FIG. 6 shows a cross section through a semiconductor body in
which a vertical trench transistor and a trench connection line are
integrated.
[0020] FIG. 7 shows a further exemplary embodiment of a component
arrangement in which a vertical trench transistor and a trench
connection line are integrated.
[0021] FIG. 8 shows a semiconductor body in which a cell array of a
power transistor and a temperature sensor which is
contact-connected by a trench connection line and is partly
surrounded by the cell array are integrated.
[0022] FIG. 9 illustrates the realization of capacitive structures
using the structures which are used for the realization of trench
connection lines.
[0023] FIG. 10 illustrates a method for producing a trench power
transistor structure and a capacitor structure in a common
semiconductor body.
[0024] FIG. 11 shows a component arrangement comprising a trench
power transistor structure and a capacitor structure which has been
produced by means of a modified method by comparison with the
method according to FIG. 10.
[0025] FIG. 12 illustrates a modification of the method according
to FIG. 10.
[0026] FIG. 13 shows the result of a modification of the method
according to FIG. 12.
[0027] FIG. 14 shows the result of a further modification of the
method according to FIG. 12.
[0028] FIG. 15 shows a further component arrangement comprising a
transistor structure and a capacitor structure.
[0029] In the figures, unless specified otherwise, identical
reference symbols designate identical component regions with the
same meaning.
DETAILED DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1A shows a cross section of a component arrangement
comprising a semiconductor body 400, on which are arranged two
wiring levels, a first wiring level 420 composed of polysilicon and
a second wiring level 410 composed of a metal, which are insulated
from one another and from the semiconductor body by insulation
layers 431, 432, for example an oxide. "Wiring level" is to be
understood hereinafter to mean a layer composed of electrically
conductive material which is patterned in such a way that a
plurality of interconnects arranged separately from one another are
present. The cross section through the metallization level 410 as
illustrated in FIG. 1B shows three of such lines 411, 412, 413,
which are arranged in a manner spaced apart from one another and
which are in each case insulated from one another by an insulation
material 433 arranged in the metallization level. In FIG. 1B, the
reference symbol 421 designates a polysilicon bridge which
conductively connects two 411, 412 of the interconnects to one
another. Said polysilicon bridge is arranged in the polysilicon
level, and thus below the metallization level, and is illustrated
in dash-dotted fashion in FIG. 1B. Conductive connections between
the metal lines 411, 412 and the polysilicon bridge 421 are
realized by vertically running connections, so-called vias, which
in each case extend in a vertical direction through the insulation
layer 432 that isolates the metallization level 420 and the
polysilicon level 410.
[0031] Although the polysilicon used for realizing the polysilicon
level 410 is highly doped, its resistivity is usually higher than
the material used for the metallization level 420. In order to
achieve a connection of the two interconnects 411, 412 which has
the lowest possible resistance, a largest possible area is required
for the polysilicon bridge 421, which can therefore lead to space
problems if a multiplicity of such "bridgings" have to be realized
in the circuit.
[0032] FIGS. 2A and 2B illustrate the basic construction of a
trench connection line, which serves, in a manner not specifically
illustrated in FIG. 2, for electrically conductively connecting two
terminal contacts arranged in a semiconductor body or on a
semiconductor body.
[0033] In FIGS. 2A and 2B, the reference symbol 100 designates a
semiconductor body having a first side 101, which is referred to
hereinafter as the front side, and a second side 102, which is
referred to hereinafter as the rear side. The semiconductor body
100 may be realized in any desired manner and may have, in
particular, a semiconductor substrate 103 and an epitaxial layer
104 applied to the semiconductor substrate, which is illustrated in
dashed fashion in FIGS. 2A and 2B.
[0034] The semiconductor body 100 has a trench 11 extending into
the semiconductor body 100 proceeding from the front side 101 in a
vertical direction v. FIG. 2A shows said trench in a section B-B
transversely with respect to its extending direction, while FIG. 2B
shows the trench in a section A-A along its extending direction. At
least one trench connection line 21, 22, 23 is arranged in said
trench, said trench connection line being insulated from the
regions of the semiconductor body 100 that surround the trench 11
by means of an insulation layer 12. The insulation layer 12 is an
arbitrary electrically insulating dielectric layer, in particular a
semiconductor oxide produced by an oxidation method or a deposited
semiconductor oxide.
[0035] The example shows three trench connection lines 21, 22, 23
which are arranged one above another in the trench 11 in the
vertical direction v of the semiconductor body, in each case two
adjacent trench connection lines from among said trench connection
lines 21, 22, 23 being insulated from one another by the insulation
layer 12.
[0036] The individual trench connection lines 21, 22, 23 within the
trench 11 may be realized such that they are completely isolated
from one another. Moreover, referring to FIG. 2B, there is also the
possibility of two of the trench connection lines, in the example
the connections 22, 23, being conductively connected to one another
by a vertical connection 23' and, after the connection point, only
one of the two connection lines, in the example the connection line
22, being continued in the trench 11 in the lateral direction. Such
a structure having two connection lines 22, 23 which are isolated
from one another in sections and continued jointly starting from a
connection point can be used for example for electrically
conductively connecting two terminal contacts (not specifically
illustrated in FIG. 2B) to one another and jointly connecting them
to a further terminal contact. For this purpose, the sections of
the connection lines 22, 23 that are led separately from one
another are connected to the terminal contacts to be connected and
the jointly continued section 22' of the two connection lines is
connected to the terminal contact to which the other two terminal
contacts are to be electrically conductively connected.
[0037] FIGS. 3A and 3B show a cross section (FIG. 3A) and a plan
view (FIG. 3B) of a semiconductor body 100, on the front side 101
of which is applied an insulation layer 103, above which separate
interconnects 31, 32, 33 are led. Said interconnects comprise for
example a metal, for example aluminum, and may be produced by
patterning an interconnect layer--which is initially applied over
the whole area--by means of an etching method using etching
masks.
[0038] Three of such interconnects 31, 32, 33 are present in the
illustrated section of the semiconductor body 100, which
interconnects run parallel to one another in sections and the two
outer interconnects 31, 33 of which are to be electrically
conductively connected to one another. For this purpose, a trench
connection line 21 is provided, which is arranged below the
interconnects in a trench 11 within the semiconductor body 100 and
which runs transversely with respect to the sections of the
interconnects 31, 32, 33 in which said interconnects run parallel
to one another. The trench 11 running below the interconnects and
having the trench connection line 21 arranged in it, and the
insulation layer 12 that insulates the trench connection line 21
from the semiconductor body 100 are illustrated in dash-dotted
fashion in FIG. 3B.
[0039] In the example illustrated, the trench connection line 21
runs in a manner spaced apart from the front side 101 of the
semiconductor body 100 in the vertical direction, with the result
that a section of the insulation layer 12 is arranged above the
trench connection line 21. In the example illustrated, in which a
further insulation layer 103 that insulates the interconnects 31-33
from the semiconductor body is present on the front side 101 of the
semiconductor body, the trench connection line 21 could also extend
as far as the level of the front side 101 of the semiconductor body
100 (not illustrated).
[0040] Vertical terminal connections 41, 42, which are referred to
hereinafter as vias, are provided for connecting the interconnects
31, 33 that are to be connected to one another to the trench
connection line 21. Said vias 41, 42 extend in the vertical
direction from the trench connection line 21 as far as the
interconnects 31, 33.
[0041] An electrically conductive connection of the interconnects
31, 33 can be realized in a space-saving manner by means of the
trench connection line 21 since no space above the front side of
the semiconductor body 100 is required for the trench connection
line 21.
[0042] The resistance of the connection line 21 is crucially
determined by the cross section of the trench connection line 21.
Said cross section can be set in particular by way of the depth of
the trench 11, enough space being available in the vertical
direction of the semiconductor body to realize a sufficiently large
interconnect cross section for the trench connection line 21.
[0043] Crossovers between two trench connection lines that do not
run parallel can also be realized in a simple manner, as is
illustrated in FIGS. 4A and 4B. FIG. 4A shows a cross section
through a semiconductor body 100 in a plan view of the front side
101. FIG. 4B shows the semiconductor body in cross section in a
vertical sectional plane D-D illustrated in FIG. 4A. Two trenches
11_1, 11_2 running perpendicular to one another are arranged in the
semiconductor body, in which trenches trench connection lines are
in each case realized in different planes. A first and second
trench connection line 21, 22 are realized in the first trench, and
are arranged in first and second vertical planes, i.e. at a first
and second vertical distance from the front side 101. In a further
plane different from the first and second planes, a third trench
connection line 23 is arranged in the second trench 11_2, which
third trench connection line crosses the first and second trench
connection lines 21, 22 at the crossover point of the two trenches
11_1, 11_2 in a manner free of contact. The reference symbol 24
designates a further trench connection line in the first trench
11_1, which further trench line connection, within said trench
11_1, does not, however, extend beyond the crossover point of the
trenches 11_1, 11_2, but rather is connected to the second trench
connection line 22 via a vertical connection 24 before the
crossover point.
[0044] The trench connection lines according to an embodiment of
the invention are also suitable for contact-connecting active
component zones of semiconductor components arranged in a
semiconductor body 100, as is explained below with reference to
FIGS. 5A and 5B. In this case, FIG. 5A shows the semiconductor body
100 in side view in cross section, while FIG. 5B illustrates a
lateral cross section through the sectional plane E-E depicted in
FIG. 5A. In this exemplary embodiment, a lateral MOSFET is
integrated in the semiconductor body 100, said lateral MOSFET
having a source zone 51 of a first conduction type, a drain zone 54
arranged in a manner spaced apart from the source zone 51 in the
lateral direction, a drift zone 53, which adjoins the drain zone 54
and is doped more weakly than the drain zone 54, and also a body
zone 52, which is arranged between the drift zone 53 and the source
zone 51 and is doped complementarily with respect to the source
zone 51. In order to control an inversion channel in the body zone
52 between the source zone 51 and the drift zone 53, a gate
electrode 55 is present, which is insulated from the semiconductor
body 100 by a gate insulation 56. In the example, said gate
electrode 55 is arranged above the front side 101 of the
semiconductor body. In the lateral MOS transistor illustrated, the
drift zone 53 serves for increasing the dielectric strength of the
component. In the case of logic components, in which only a low
dielectric strength is required, said drift zone can be dispensed
with, if appropriate.
[0045] In the case of this component, the source and drain zones
51, 54 are respectively contact-connected by trench connection
lines 21, 25. Said trench connection lines are respectively
arranged in trenches 11, 14 and electrically conductively connected
to the source and drain zones 51, 54 via terminal connections 41,
45. Moreover, the trench connection lines are insulated from the
semiconductor body 100 by means of insulation layers 12, 13. In
addition, a further insulation layer is present, which covers the
trench connection lines 21, 25 in the direction of the front side
101 in order to insulate the trench connection line for example
from further interconnects (not illustrated) which may be arranged
above the front side 101.
[0046] The trench connection lines 21, 22 serve for example for
connecting the source and drain zones 51, 54 to active component
zones of further components (not illustrated) integrated in the
semiconductor body, in order thereby to realize an integrated
circuit whose wiring does not require any space above the
semiconductor body. Furthermore, there is also the possibility of
leading the trench connection lines to the front side in a manner
spaced apart from the source and drain zones 51, 54
contact-connecting them, in order to connect them, at said front
side, to an external terminal potential via terminal contacts, as
is illustrated for the trench connection line 21 in FIG. 5c.
[0047] The trench connection lines described above at least
partially may be produced by the same process steps as the gate
electrode of a trench power transistor integrated in the
semiconductor body. This will be explained below with reference to
FIGS. 6 and 7.
[0048] FIG. 6 shows in side view a semiconductor body 100, in which
are integrated a transistor structure of a vertical trench power
transistor 60 and trench connection lines 21, 22, 23 for the wiring
of logic components that are not specifically illustrated and are
likewise realized in the semiconductor body 100. The transistor
structure 60 is constructed in cellular fashion and comprises a
number of in each case identical transistor cells. Each transistor
cell comprises, in the vertical direction of the semiconductor body
100, proceeding from the front side 101, a source zone 61 of a
first conduction type, a body zone 62 of a second conduction type
complementary to the first conduction type, a drift zone 63 of the
first conduction type, and also a drain zone 69 of the first
conduction type, which is doped more highly than the drift zone 63.
In order to realize a MOSFET, the drain zone 69 is doped
complementarily with respect to the body zone 62, while the drain
zone 69 is doped complementarily with respect to the drift zone 63
in order to realize an IGBT.
[0049] In order to control an inversion channel in the body zone 62
between the source zone 61 and the drift zone 63, a gate electrode
64 is present, which is arranged in a trench extending into the
semiconductor body in the vertical direction proceeding from the
front side 101. Said gate electrode 64 is insulated from the body
zone 62 by means of a gate insulation layer 65. Two field
electrodes 66, 67 are present in the trench below the gate
electrode 64, said field electrodes being insulated from the drift
zone 63 by means of a field plate insulation layer 68.
[0050] In the present case, the semiconductor body 100 comprises a
highly doped semiconductor substrate 103, which forms the drain
zone 69, and also a more weakly doped epitaxial layer 104, which is
applied to the semiconductor substrate 103 and which forms the
drift zone 63 in sections and in which the source and body zones
61, 62 are realized in the region of the front side 101. The
transistor structure illustrated in the left-hand part in FIG. 6 is
known in principle and described in DE 103 39 455 C1, which is
incorporated herein by reference.
[0051] The gate electrode 64 and the field electrodes 66, 67 are
produced in a known manner by etching a trench starting from the
front side of the semiconductor body 100, by producing a dielectric
layer on sidewalls of the trench and by depositing of electrode
layers, which form the field electrodes 66, 67 and the gate
electrode 64. For the arrangement of FIG. 6 first the lower
(second) field electrode 67 is produced by depositing a first
electrode layer. This electrode layer may be etched back in a
vertical direction in order to adjust the dimension of the lower
field electrode in the vertical direction. Subsequently a
dielectric layer is produced on the lower field electrode 67, for
example, by depositing a dielectric or by partially oxidizing the
lower field electrode 67. In a corresponding manner the upper
(first) field electrode 66 and the gate electrode 64 may be
produced. By means of the same process steps which are used for
producing the gate electrode 64 and the field electrodes 66, 67 in
the trenches of the transistor structure, at least parts of the
trench wiring or the trench connection lines are produced, namely
those parts of the trench wiring which--corresponding to the field
electrodes 66, 67 and the gate electrode 64--extend in a lateral
direction of the semiconductor body 11 and therefore run parallel
to the front side 101.
[0052] The body zones 62, as well as the source zones 61 and the
connecting zones 70 may be produced before or after producing the
trench structures with the gate and field electrodes 64, 66, 67 and
the connection lines 21, 22, 23. These semiconductor zones may be
produced by implantation and/or diffusion of dopants into the
semiconductor layer 104.
[0053] Those section of the trench connection lines, which extend
in a vertical direction 100 of the semiconductor body, and which
therefore run perpendicular to the front side 101, may be produced
by simple modifications of the method discussed above. Such a
section running perpendicular to the surface, for example, is the
section 23' of FIG. 2B, which connects two lines 22, 23 which are
parallel to one another. Such connection may be produced by
removing a dielectric separating the lines 22, 23 in an area, in
which the connection 23' is to be produced, before an electrode
layer for producing the second connection line 22 is deposited.
Alternatively, producing a dielectric in the area of this
connection 23' may be prevented after an electrode layer forming
the lower line 22 has been deposited.
[0054] The aforementioned DE 103 39 455 C1 describes connecting the
individual field electrodes of the transistor structure to
different electrical potentials. In the case of the arrangement
illustrated in FIG. 6, the field electrodes 66, 67 can be
connected, in a manner not specifically illustrated, via trench
connection lines to suitable potential sources that provide the
desired different potentials. Said potentials may be generated for
example using a zener diode chain comprising a plurality of
series-connected zener diodes across which a supply voltage is
present. In this case, different potentials can be tapped off at
intermediate taps of the zener diode chain, that is to say at
connection points of in each case two zener diodes directly
connected in series.
[0055] The source zones 61 of the transistor structure are jointly
connected to a source electrode 71, which also makes contact with
the body zone 62 via highly doped terminal zones 71 in order
thereby to short-circuit source and body in a known manner. In the
logic portion, for which trench connection lines 21, 22, 23 are
illustrated in a representative manner in FIG. 6, there is the
possibility of arranging interconnects above the front side 101 of
the semiconductor body in accordance with FIGS. 3A and 3B.
[0056] FIG. 7 shows a further semiconductor component arrangement,
in which a trench transistor structure and trench connection lines
are integrated in a common semiconductor body 100. The trench power
transistor structure illustrated in FIG. 7 is known in principle
from DE 100 63 443 A1 and differs from that illustrated in FIG. 6
by virtue of the fact that an electrode 64A is present, which, in
the upper region of the trench, that is to say in the region of the
body zone 62, is insulated from the body zone 62 by a gate
insulation layer 65, which is thin in comparison with a field plate
dielectric 68, and acts as a gate electrode there, while in the
lower region of the trench it is insulated from the drift zone 63
by the thicker field plate dielectric 68 and acts as a field plate
64B there. In the upper region of the trench, the gate electrode
has a forked structure enclosing a further electrode section 64C in
the lateral direction, said further electrode section usually also
being connected to gate potential.
[0057] In the example illustrated, the drain zone 69 of the
transistor structure 60 is realized as a buried highly doped zone
which is led to the front side 101 at the edge of the cell array
comprising the individual transistor cells of the transistor
structure.
[0058] The method for producing this gate electrode formed in
forked fashion with the further electrode 72 enclosing it can be
used correspondingly for realizing at least parts of two trench
connection lines 21, 22 that are electrically insulated from one
another, and that are arranged in a further trench 11 which is
spaced apart from the trench transistor structure 60. The method,
in particular, is suitable for producing those parts of the
connection lines 21, 22 that run parallel to the front side of the
semiconductor body.
[0059] In the component structures of FIGS. 6 and 7 the trench
transistor structure besides a gate electrode 64 comprises a field
electrode, which together with the gate electrode 64 is disposed in
a common trench. The trench connection lines disclosed in these
figures comprise a number of lines which corresponds to the number
of gate and field electrodes of the transistor structure. It should
be mentioned in this connection that the transistor structure not
necessarily comprises a field electrode. Thus, only a gate
electrode may be produced. In this case the trench wiring comprises
only one line.
[0060] Furthermore, the number of parallel trench connection lines
may be lower than the number of electrodes of the transistor
structure. In this case the method is modified in such a manner
that an area of the semiconductor body 100, in which the trench
wiring is produced, is masked during deposition of at least one of
the electrode layers forming the electrodes. Alternatively, the
method is modified in such a manner that one of the deposited
electrode layers is removed in this area.
[0061] A method in which at the same time with producing an
electrode structure 64-66 in a transistor trench of a semiconductor
body 100 at least parts of a trench wiring structure 21-23 is
produced, results to a component structure which comprises
connection lines, that at least partially or in sections have
identical geometrical structures as the electrode structure 64-66
of the transistor. The connection lines may be comprised of the
same material as the electrodes 64-66 of the transistor and may be
insulated by the same dielectrical material against one another and
against the semiconductor material of the semiconductor body 100.
The electrodes 64-66 and the connection lines 21-23, for example,
are comprised of a doped polysilicon of the same doping
concentration.
[0062] A further possible application of the trench connection
lines explained above is explained below with reference to FIGS. 8A
to 8C. FIG. 8A shows in plan view a semiconductor body 100, in
which a cell array comprising transistor cells constructed
identically in each case is realized. Said transistor cells may be
for example transistor cells in accordance with FIGS. 6 and 7 or
arbitrary further transistor cells. A temperature sensor 80 is
present in a manner surrounded by the transistor cells of said
transistor cell array, said temperature sensor serving for
detecting the temperature within the cell array. With regard to a
temperature measurement that is as exact as possible, it is
desirable in this case for the temperature sensor 80 to be
surrounded as completely as possible by the transistor cells of the
cell array in the lateral direction of the semiconductor body 100.
In this context, it is necessary to avoid wide connection lines at
the surface of the semiconductor body since no transistor cells can
be realized below said connection lines. The trench connection
lines explained above make it possible to realize a space-saving
line routing to the temperature sensor 80. FIG. 8B shows said
trench connection lines 21, 22 in cross section, each of said
connection lines respectively contact-connecting one of two
terminal contacts of the temperature sensor 80.
[0063] Referring to FIG. 8C, the temperature sensor 80 is realized
for example as a pn junction with an n-doped zone 81 and a p-doped
zone 82, said pn junction being operated in the reverse direction.
This makes use of the fact that the reverse current of such a
reverse-biased pn junction raises exponentially with the
temperature. The upper one of the trench connection lines 21, 22
arranged in the trench 100 makes contact with the n-type zone 81,
for example, while the lower one makes contact with the p-type zone
82 of the temperature sensor 80.
[0064] The trench connection lines discussed above which, at least
partially, are produced by the same process steps as an electrode
structure of a trench transistor may also serve as capacitive
structures within the semiconductor body 100, as will be explained
in the following.
[0065] FIG. 9A shows a cross section through a semiconductor body
100 having a trench 11 with trench connection lines 21-23 arranged
therein. In each case two adjacent trench connection lines from
among said trench connection lines form a capacitor electrode of a
capacitor. This presupposes that the two adjacent trench connection
lines are in each case electrically contact-connected only at one
side, while the other side of the connection line remains open.
This is illustrated in side view in cross section in FIG. 9B. In
this example, the trench connection lines in each case end within
the trench 11, while their other ends are led to the front side 101
in order to be contact-connected there. The capacitor dielectric is
formed by the insulation layer or dielectric layer 12 arranged
between the individual trench connection lines 21-23 within the
trench 11.
[0066] The circuit symbols of the capacitors formed by in each case
two adjacent trench connection lines are likewise depicted in FIG.
9A.
[0067] What is more, there is also the possibility of using a
semiconductor region 91 surrounding the trench, which semiconductor
region is preferably doped complementarily to a basic doping of the
semiconductor body 100, as a capacitor electrode and of using the
trench connection lines 21, 22, 23 in each case as other capacitor
electrode, said trench connection lines optionally being connected
to a common electrical potential in order to realize a capacitive
structure having a particularly high capacitance. In FIG. 9A, the
reference symbol 92 designates a terminal of the semiconductor
region 91 that surrounds the trench and forms a capacitor
electrode.
[0068] What is more, there is also the possibility of realizing a
plurality of separate capacitors by connecting the individual
trench connection lines 21-23 to separate electrical
potentials.
[0069] A particularly effective method for realizing a power
transistor structure and a capacitor structure in a common
semiconductor body, in which largely common method steps are used
for producing the power transistor structure and the capacitor
structure, is explained below with reference to FIGS. 10A to
10E.
[0070] FIG. 10A shows in side view a cross section through a
semiconductor body 200 having a first side 201, which is referred
to hereinafter as the front side, and a second side 202, which is
referred to hereinafter as the rear side.
[0071] In the example, the semiconductor body 200 comprises a
semiconductor substrate 205 and an epitaxial layer 206 applied to
the semiconductor substrate 205. In FIG. 10A, the reference symbol
203 designates a section of the semiconductor body in which a
transistor structure is intended to be realized, and the reference
symbol 204 designates a section of the semiconductor body 200 in
which a capacitor structure is intended to be realized. Said
sections 203, 204 are referred to hereinafter as transistor section
and capacitor section of the semiconductor body 200.
[0072] FIG. 10A shows the semiconductor body 200 after first method
steps involving the production of trenches 211, 212 in the region
of the transistor section 203 and trenches in the region of the
capacitor section 204. Said trenches 211, 212 are referred to
hereinafter as transistor trenches 211 and capacitor trenches
212.
[0073] Said trenches 211, 212 are produced in a known manner by
applying a patterned etching mask 300 to the front side 101, for
example an oxide hard mask, and subsequently etching the
semiconductor body 200 in the regions in which the etching mask 300
has cutouts which define the trenches. In this case, the dimensions
of the trenches 211, 212 in a lateral direction of the
semiconductor body 200 are dependent on the dimensions of the
openings of the etching mask 300.
[0074] The trenches 211, 212, running in elongated fashion in a
direction perpendicular to the plane of the drawing illustrated in
FIG. 10A, can be produced in such a way that the transistor
trenches 211 have a width identical to that of the capacitor
trenches 212, but the trenches 211, 212 may also have different
widths. Said trenches 211, 212 are preferably produced in such a
way that the capacitor trenches 212 are wider than the transistor
trenches 211. In this case, the "width" denotes the dimensions of
the trenches 211, 212 transversely with respect to their
longitudinal direction.
[0075] The transistor and capacitor trenches 211, 212 may
furthermore also have different depths, that is to say different
dimensions in a vertical direction of the semiconductor body 200.
When carrying out an anisotropic etching method for producing the
trenches 211, 212, the depth of the latter can be set by way of the
width of the cutouts in the etching mask. For a given etching
duration, the trench depth is all the greater, the wider the
cutouts.
[0076] FIG. 10B shows the semiconductor body 200 after further
method steps involving the production of a dielectric layer 221 in
the capacitor trenches 212 and on the front side 201 of the
capacitor section 204. Said dielectric layer 221 is an oxide layer,
for example, which is produced after the removal of the etching
mask (reference symbol 300 in FIG. 10A) by thermal oxidation of
uncovered areas of the capacitor section 204, that is to say the
front side of the semiconductor body 200 in said capacitor section
204 and the sidewalls of the trenches 212. Said oxidation layer 221
grows onto the semiconductor body in the capacitor section 204,
semiconductor materials "being consumed". The dash-dotted line in
FIG. 10B shows the course of the surface of the capacitor section
204 before the thermal oxidation for the production of the
dielectric layer 221.
[0077] Before the thermal oxidation of the capacitor section 204 is
carried out, an oxidation protection layer 230 is applied to
uncovered surface regions of the transistor section 203, which
layer prevents the production of an oxidation layer on the surface
of the semiconductor body 200 in the transistor section 203. Said
oxidation protection layer 230 is a nitride layer, for example.
[0078] FIG. 10C shows the semiconductor body 200 in cross section
after further method steps involving the removal of the oxidation
protection layer 230 and the production of a gate dielectric layer
241 at the sidewalls of the transistor trenches 211. Said gate
dielectric layer is an oxide layer, for example, which is produced
by means of a thermal oxidation, the oxidation conditions being set
such that the gate insulation layer is thinner than the capacitor
dielectric layer 221 of the capacitor section 204. On account of
the oxidation of the semiconductor body in the transistor section,
an insulation layer also arises above the front side 201 of the
semiconductor body, which is removed again in a later method
step.
[0079] In further method steps, the result of which is illustrated
in FIG. 10D, an electrode layer 222, 232 is jointly deposited onto
the capacitor section 204 and the transistor section 203. Said
electrode layer forms a capacitor electrode in the capacitor
section 204 and the later gate electrode of the power transistor
structure in the transistor section.
[0080] The capacitor structure is completed after these method
steps. Said capacitor structure is formed by the capacitor
electrode 222, the capacitor dielectric 221 and a semiconductor
zone 223 surrounding the trenches with the capacitor dielectric
221. Said semiconductor zone 223 is for example doped
complementarily with respect to the semiconductor substrate 205 and
doped complementarily with respect to the epitaxial layer 206 in
the region of the transistor structure 203.
[0081] The epitaxial layer 206 forms the later drift zone of the
component in sections in the region of the transistor structure. A
complementary doping of the drift zone and the semiconductor zone
223 that forms a second capacitor electrode avoids shunt currents
between these component regions within the semiconductor body
200.
[0082] FIG. 10E shows the semiconductor body 200 in cross section
after the performance of further method steps known in principle
for completing the transistor structure after the production of the
trenches, the gate insulation layer 231 and the gate electrodes
232. Said method steps comprise the removal of the electrode layer
232 from the front side 201 of the semiconductor body 200 in the
region of the transistor trenches. Said removal may be effected by
means of an etching method, by way of example. In this case, said
electrode layer is preferably etched back to an extent such that
the gate electrodes 232 end below the front side 201 of the
semiconductor body in the trenches 212.
[0083] The production of the transistor structure additionally
comprises the production of a body zone 233 doped complementarily
with respect to a basic doping of the epitaxial layer 206, and also
the production of source zones 234 which are doped complementarily
with respect to said body zone 233 and which adjoin the trenches
with the gate electrode 232 in a known manner. Moreover, a source
electrode 236 is produced, which makes contact with the source
zones 234 and is insulated from the gate electrodes 232 by further
insulation layers 237 above the gate electrodes 232. The source
electrode 236 can also make contact with the body zone 233 in a
known manner in order to short-circuit source 234 and body 233.
[0084] The transistor structure has a cell structure comprising a
multiplicity of identically constructed transistor cells each
having a gate electrode 232 arranged in a transistor trench. In
this context it should be pointed out that the electrode layer can
remain, in an edge region of the cell array, above the front side
of the semiconductor body 200 in a manner that is not specifically
illustrated.
[0085] The electrical equivalent circuit diagram of the power
transistor is likewise illustrated in FIG. 10E. The drain zone of
said power transistor is formed by the semiconductor substrate 205.
The power transistor illustrated in FIG. 10E is realized as an
n-channel MOSFET. Said transistor may, of course, also be realized
as a power IGBT, in which case the semiconductor substrate is to be
realized complementarily with respect to the epitaxial layer that
forms the drift zone 235.
[0086] FIG. 11 shows a component arrangement comprising a power
transistor structure and a capacitor structure in a common
semiconductor body 200, which is produced by means of a modified
method by comparison with the method according to FIG. 10. In this
method, the electrode layer 222 is also etched back to below the
upper edge of the dielectric layer 221 in the region of the
capacitor structure, whereby separate electrode sections 222A, 222B
are produced in the individual trenches. A plurality of separate
capacitors which have a common capacitor electrode with the
semiconductor zone 223 can be realized as a result.
[0087] FIGS. 12A to 12C illustrate a modification of the method
explained above with reference to FIG. 10. Referring to FIG. 12A,
in this method, after the production of the transistor and
capacitor trenches 211, 212, firstly the gate insulation layer 231
is produced, as a result of which an insulation layer 224 is also
produced on the front side 201 and in the capacitor trenches of the
capacitor section 204.
[0088] Referring to FIG. 12B, the electrode layer 232 is
subsequently deposited, which forms the later gate electrodes in
the transistor section. In the transistor section, said electrode
layer protects the gate insulation layer during subsequent method
steps for producing the capacitor dielectric in the capacitor
section.
[0089] FIG. 12C shows the semiconductor body after the production
of said capacitor dielectric 221 and an electrode 225 applied to
the capacitor dielectric 221, a function of said electrode
corresponding to the electrode 222 in accordance with FIG. 10E. The
production of the capacitor dielectric 221 is preceded by the
removal of the insulation layers 224 and the electrode layer 232 in
the region of the capacitor structure. The production of the
capacitor dielectric 221 may be effected in the manner explained by
a thermal oxidation or else by deposition of an oxide layer, such
as, for example, TEOS layer (TEOS=tetraethoxysilane). After the
production of the capacitor dielectric 221, the electrode layer 225
is deposited in a conventional manner. The capacitor structure is
completed after the conclusion of these method steps.
[0090] It goes without saying that, in accordance with the
exemplary embodiment in FIG. 11, there is also the possibility of
subdividing this capacitor electrode in order to realize a
plurality of capacitors in the capacitor section 204.
[0091] The further method steps for completing the transistor
structure proceeding from the structure in accordance with FIG. 12C
correspond to the method steps explained with reference to FIG.
10E.
[0092] FIG. 13 shows as the result a component structure in which
the gate dielectric layer 231 and the capacitor dielectric 224 are
produced by the same method steps. Such a component may be
obtained, proceeding from the method according to FIG. 12, by
virtue of the fact that the method steps explained with reference
to FIG. 12, involving the production of the gate dielectric 231 in
the transistor trenches 211 and the insulation layer 224 in the
capacitor trenches by means of common method steps, and involving
the production of electrode layers 232, 222 in the transistor and
capacitor trenches 211, 212 by means of further common method
steps, are followed directly by the method steps explained with
reference to FIG. 10E for completing the transistor structure. In
this component, the insulation layer produced during the production
of the gate dielectric 231 in the transistor trenches forms the
capacitor dielectric, and the electrode 222 produced during the
production of the gate electrode 232 forms one of the capacitor
electrodes. Said electrode 222 may be maintained as a one-piece
electrode, as is illustrated in FIG. 13.
[0093] Referring to FIG. 14, there is furthermore the possibility
of etching back said electrode 222 in such a way that individual
electrodes arise in the capacitor trenches 212 in order thereby to
realize a number of individual capacitors. In this case, the
semiconductor region 223 surrounding the trenches forms a common
electrode for the individual capacitors. In the component in
accordance with FIG. 14, said semiconductor region 223 is
contact-connected by a further electrode 227, which is arranged
above the semiconductor body 200 and which is insulated from the
electrodes 222 arranged in the trenches in a region above the
semiconductor body 200 by means of insulation layers 228.
[0094] The methods of FIGS. 10 to 14 result to component
arrangements having a trench transistor structure and a capacitor
structure, with the capacitor structure comprising at least one
capacitor electrode disposed in a trench and having at least
partially the same geometrical basic structure as the electrode
structure of the transistor. "Same geometrical basic structure" in
this connection means, that the geometrical structures in general
are the same but may vary in terms of their lateral or vertical
dimensions. The materials of the electrode structure of the
transistor and the materials of the electrode structure of the
capacitor are identical.
[0095] FIG. 15 shows a vertical cross section through a further
component arrangement having a transistor structure and a capacitor
structure. In this case, the transistor structure corresponds to
the transistor structure already explained with reference to FIG. 7
and comprises a number of transistor cells having gate electrodes
64 arranged in trenches, which merges into a field plate 64B in the
vertical direction of the semiconductor body and which encloses a
further electrode section 64C in forked fashion.
[0096] The capacitor structure has capacitor electrodes which are
arranged in trenches and whose geometry corresponds to that of the
gate electrodes 64A, field plates 64B and electrode sections of the
transistor structure and which are designated by the reference
symbols 241, 242, 243 in FIG. 15. Depending on the
contact-connection of the individual electrodes, different
capacitors can be formed by this arrangement. If the forked
electrodes 241, 242 and the electrode 243 surrounded by the latter
are contact-connected separately, then a respective capacitor is
formed by each of said forked electrodes 241, 242, by the electrode
243 surrounded by the latter, and by the intervening
dielectric.
[0097] The trenches with the electrodes 241, 242, 243 are
surrounded, in the example, by a semiconductor zone 223 doped
complementarily with respect to a basic doping of the semiconductor
body 200 and in the example complementarily with respect to the
drift zone 63 of the transistor structure. Said semiconductor zone
223 can be contact-connected via a highly doped terminal zone 226
and forms a capacitor electrode. In this arrangement, a capacitor
is formed by the semiconductor zone 223, a dielectric 244 arranged
in the trenches, and also the forked electrode 241, 242.
[0098] The electrode structure produced in trenches together with
the electrode structure of the trench transistor--as explained
above--at least partially may be used as a wiring structure or as
an electrode structure of a capacitor. However, such electrode
structure is not limited to this use.
[0099] While the invention disclosed herein has been described in
terms of several preferred embodiments, there are numerous
alterations, permutations, and equivalents which fall within the
scope of this invention. It should also be noted that there are
many alternative ways of implementing the methods and compositions
of the present invention. It is therefore intended that the
following appended claims be interpreted as including all such
alterations, permutations, and equivalents as fall within the true
spirit and scope of the present invention.
* * * * *